Silver-Decorated CFA/DA/NBP Nanocomposite for Adsorptive Removal of Methylene Blue Dye from Water

A multifunctional nanocomposite, CFA/DA/NBP@Ag, was synthesized via a simple route involving coal fly ash (CFA) functionalized with dopamine (DA), incorporation of neem bark powder (NBP), and in situ reduction of silver nanoparticles (AgNPs) using silver nitrate. The composite effectively adsorbed methylene blue (MB) dye from water, achieving 80% removal within 210 minutes. UV–Vis spectrophotometry (664 nm) was used to monitor dye removal, and adsorption efficiency was found to increase with pH (68%, 80%, and 89% at pH 4, 7, and 9, respectively). PXRD confirmed the presence of Ag, NBP, DA, and CFA phases, while SEM revealed mostly spherical particles (20–50 nm). Kinetic analysis followed pseudo-first-order behavior with a rate constant of 0.0089 min⁻¹. These results underscore the potential of CFA/DA/NBP@Ag as a sustainable and low-cost adsorbent for wastewater treatment.